Method of refining petroleum



May 10, 1927.

W. E". LUMMUS METHOD OF REFINING IETROLEUM Filed May 21, 1923 2 sheets-sheet 1 May l0, 1927. 1,628,252

w. E. LUMMUS METHOD 0F REFINING PETROLEUM Filed May 21. 1923 2 Sheets-Sheet 2 [5J CON.

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r densing points and which are usuall Patented May 1o, 1927.

i .UNITED STATES- WALTER. E. LUMMUS, OF LYNN', MASSACHUSETTS.

METHoDoF BEFINING rE'rnoLEUiu.

Application nica my 21, 192s. sensi-n. 640,332'.

The present invention relates to an improved method of refining petroleum oils. The lower boiling mixed petroleum vapors are difficult or impractical to condense completely by usual methods and some of them are customarily lost in petroleum refining and in the recovery of oils from natural gas. Such vapors usually consist of mixtures of hydrocarbons having boiling or condensing points ranging from 800o F. to 0 F. at atmospheric pressure and therefore contain vapors that alone would be uncondensible without refrigeration or pressure, or both. In refining petroleum oils by distillation, the vapors from the stills are liquefied by passing them through one or more watercooled condensers, usually consisting of a.

coil or coilsof pipe of considerable aggregate length. This process of cooling and condensing affects first those portions of the mixturethat are most easily condensed, then the surviving vapors that are less readily condensed, and soon, with the result that the fractions having lowest lboiling or colrlb t e most valuable, tend to concentrate an survive as vapor that is uncondensible at tht` temperatures and pressures employed in the condenser, and therefore escape'and are lost. The value of some of these "so-called uncondensible vapors is sometimes so great that their recovery, by economical means, would add materially to the profit or lower the cost of all the products of the operation with which they are concerned.

The principal .object of the invention is to recover the lmore reluctantly condensible vapors resulting from the distillation of petroleum oils. Casinghead oils are condensed fromgases and vapors by a process involving the use of compression and refrigeration, and the products contain highly volatile foils or light vapors which are reluctantly condensible. Such vapors are lost r when the pressure is-reduced, or they are lost when the oils are mixed with warmer oils, inasmuch as they have low boiling points and -tend to evaporate from the mixture. The loss is due not alone to the escape ot' such light vapors or low boiling oils, but. in their escape from the mixture they carry off with them certain quantities of higher boiling oils which increase the losses due to their. evaporation, -J

Another yobject of the invention is toproduce a; methodof refining petroleum oils by virtue ofuwhich the light 'vapors of low boiling oils are condensed, absorbed or 'dissolved in higher boiling foils/of such character as to retain them in so ution or absorbed or liquefied condition. L i 'i Other. objects of the invention will be apparent from the/'following description of the method, which'consists in the rocess of refining petroleum oils hereinaflt and particularly defined in the claims.

In -the accompanying drawings Fig. 1 illustrates a petroleum oil distilling apparatus of the continuous type for practicing the method of the present invention; Figs. 2, 3 7 0 and 4 illustrate other forms of apparatus by neais of which the invention may be pracice Referring to Fig. 1, the still 10- is heated by a furnace 11 controlled by a valve 12 75.'

and discharges its vapors through the vapor pipe 13 to the bottom of a distilling column or contact path apparatus 14 from which the effluent vapors pass through the vapor pipe 15 to the condenser( The return pipe 80 16 permits' any liquid collecting in the bottom of the column to return to the still. The stil-l is provided with an overflow pipe 17. The vapors efliuent from the distilling column 14 are introduced into the cooling zone 85 of a condenser 18 Where a portion of the vapor is condensed and flows out into the bottle 19 from which a portion of the condensate Hows through the pipe 20 to piecesV of apparatus hereinafter referred to. The condensate flowing from the condenser 18 coinprises as -its principal ingredient the more readily condensible vapor constituents of the vapors effluent from the column '14. A second portion of this same condensate flows through the pipes 21 and 22 to the top of the column 14. The petroleum oil mixture which is introducedto the apparatus is preheated by passing through the condenser ,18. It is introduced through lthe oil Y pipe 23 and passes through the condenser and flows through the ipe 24 Kto an intermediate chamber of t e column 14. As shown; the oil may be introduced at any one of three compartments of the column. rThis a. paratus is continuous and in operation, oil flows in through the oil pipe to the column Where it iS divided into two er deseribed 65 Cil etliuents, a vapor-effluent, which passes out through the vapor pipe 15, and a liquid eliiuent, Which passes out through the vapor pipe 16 to the still, from which latterthe liquid etlluent from the column finally finds its way out of the apparatus. The uncondensed vapors from the condenser 18 pass through the vapor pipe 25 to the cooling `zone of a condenser 2G cooled by a stream of Water entering throughl the pipe 27 and passing out through the pine 28. In this condenser 26 a further portion of Athe cittaent vapors of thegcolumn is condensed and the condensate passes into the bottleA 29 along With a certain last portion of the elliuent vapors from the column which passes out of the second condenser 26V uncondensed. These are the. more reluctantly condensible vapors' eiiluent from the column. I A portion of the comlensate` from the condenser 26 flows through the pipe 30 and is discharged as a second condensate product. A second portion'of the condensate from the second 4condenser 26 flows into the pipe 22 and is returned to the top of .the column therethrough. The eilluent uncondensed vapors from the second condenser 26 pass through the vapor pipe 31- to the column scrubber 32, being intro uced at the bottom of this scrubber. A portion of the condensate from the first condenser 18 passes .throughthe pipe 20 to the cooler 33 from which it is discharged into the bottle 34 from which a portion 1s discharged as first distillate through the pipe 35. second portion f this rst distillate is-led through the pipe 36 to the top of the col,

umn scrubber 32 where it trickles down through the scrubber and absorbs, dissolves or condenses the more reluctantly condensible vapors flowing into the bottom of the scrubber. The scrubber discharges through the pipe 37 a product which lconsists of the condensed, absorbed oru dissolved vapors entering the scrubber from the second condenser contained in the liquid ellluent from the non-adjacentv condenser 18, i. e., the non-adjacent fractional condensate from the first condenser.

The apparatus thus described operatesl on the vapor flowing from the distilling column and condenses it in a plurality of steps. The condensate with the apparatus shown is thus divided into two portions, `which may be referred to as a No. 1 distillate from the first condenser and a N o. 2 distillate from the second condenser, The third product which may be called No. 3 distillate consists of N o. 1 distillate to which has been added the reluctantly condensible vapors effluent from the last condenser. The whole vapor ettluent from the column, for example, may be regarded as gasoline, and No. 1 distillate would have a certain boiling, oint, N o. 2 distillate would have a slightly igher boiling point,

and No. 3 distillate might'have a boiling.

point the same as N o. 2 distillate.

'lhe separation of the three `products is of no significance. The object of the method is to liquefy the lighter eiiiuent vapors from condensing action of a distillate non-adja` cent thereto. In myl prior Patent No. 1,336,- 3Q0, the more reluctantly condensible materials comprised in the vapor substance introduced into the condenser were subjected to the absorbing action^of the entire liquid eiiluent from th'e condenser. The method of that patent was particularly intended for use in treating vapors present in coke oven gases suchas benzol t'oluol and associated high boiling oils, each of which has a distinct precise boiling'point. It was also adapted for use in liquefying ether, carbon disulphide and other volatile liquids from a vapor state either alone or mixed with non-condensible gases. lVhile the present method is one embodiment or form of the method of said patent, it has been found that, in treating petroleum oils a non-adjacent condensate is more etlicient in condensing, dissolving or absorbing the more reluctantly condensible 'portion of the vapors. In fact, the more remote the condensate or the higher its'boiling point, the greater its capacity to absorb, dissolve or condense the more reluctantly condensible vapors. In the former patent, therefore, the vapor substance admittedywas in part condensed, and the uncondensed porition was treated by the condensed portion tand specifically by the condensate of the identical substance, whereas in the present invention the more reluctantly condensible vapors contained in the` vapor substance. admitted to the condensers are subjected to the absorbing, dissolving or condensing action of non-adjacent fractional condensatcs of suoli vapor of higher boiling point.

rlhe important feature of the invention resides in the increased recovery of the reluctantly condensible vapors by dissolving, condensing or absorbing them in a nonadiaeent condensate from which such vapors have been separated.

It is to be observed that the. saving of the more reluctantly condensible vapors is effected by introducing them intol and unitmg them with a product or a. substance which, when it shall havev absorbed such lighter oil vapors, will constitute a final product, and so far as the invention, viewed in its broader aspects, is concerned, it is immaterial if all three ot the distillate products of this apparatus are discharged into a common receptacle, this product being increased 111 amount by the recovery of the more rei densing the more reluctantl luctantly condensible vapors of the original distillate, which, in fact, are the most valuable condensates of such distillate. In the apparatus illustrated in Fig. 2 ther are three condensers 50, 51 and 52 employed.l The uncondensed gas or vapor from the last condenser is conducted by means of the pipe 53 to the column scrubber 54 where it is subjected to the absorbing-condensing and dissolving action of a mixture of the non-adjacent condensates from condensers and 51. B the use of the cocks in the condensate pipes rom the condensers 50 and 51, the condensate from either of these condensers may be employed in the scrubber or their mixture in any proportions desired, a portion of each being returnedto -the column 14 as before. The condensate of the first condenser is discharged at 55, that from the second condenser at 56 and that from the third condenser at 57 and that from the column scrubber at 58.

If it is desired to use Athe more remote condensate for dissolving, absorbing or concondensible va ors of the vapor mixture e uent from the co umn 14, then the cock in the condensate pipe from the condenser 51 will be closed and the condensate from the condenser 50 will be employed in the scrubber. Again, the condensate from the condenser 51 -only may be used, land the condensate of the most remote condenser may be drawn off at o5. Agaim a certain portion of the condensate from thelcondenser 50 and 51 may be used,

more of one than the other if desired, and

parts of these condensates drawn olf as separate products. l

The characteristic feature of the specific method susceptible of being practiced by. the apparatus of Fig. 2 is the) recovery of the more reluctantly Acondensible vapors iii a mixture of nonadjacent condensates.

In the apparatus of Fig. 3 which`is employed in practicing still another specific modification of the process, three condenseis 60, 61 and-62 are employed, and the vapor from the last condenser is conducted by means of the pipe 63 to the column scrubber 64 Where the vapors are subjected to the scrubbing action of the condensate of the A next lower'condenser. From this scrubber any uncondensed vapors are conducted by means of the pipe 65 to the second column scrubber 66, where they aresubjected to the scrubbing action of a condensate from the condenser 60. In this method the recovery is accomplished in progressive fashion, the more i'el-uctantl condensible vapors being condensed absor ed or 4dissolved in the more remotel non-adjacent condensates. In the apparatus illustrated in Fig. 4 still another specific mode of practicing the pres` ent invention is diagrammatically illustrated. Here the vapors eluent from the '14 are to the condenser 71. In this,

the pipe 73` and flows out through distilling column or contact path apparatus conveyed through the va or pipe condnser a portion of the vapors are condensed and returned by the reflux pipe 72 to the-top ofthe contact path apparatus 14. A cooling fluid is introduced into this condenser through 74; The uncondensed vapors from denser 71 flow through the vapor pipe 75 to the bottom of a second distillingl column or contact .(path a paratus 76. Here the vapors rise an con ensates descend through the apparatus 76 and flow out through the.

liquid effluent pi e 7 7. These liquid effluents are cooled in t e cooler 78 for luse ina column scrubber., lThe vapor ellluent fromthe pipe the con by the pipe 84 to the second condenser 85 where a further portion of the vapors is condensed and discharged at 86. The re? maining vapors uncondensed by the second condenser 85 are conducted by the vapor J pipe 87 to the column scrubber 88, where they are subjected to the scrubbing action of the condensate eluent from the contact path apparatus76 above referred to, which ias previously been cooled in the cooler 78 and is now conducted by a pipe 89 to the top of the column scrubber 88. In this column scrubber the vapors eilluent from the second condenser are subjected to the dissolving,

condensing and absorbing action of the ref mote condensate, and the resulting product is discharged at 90.

Here it will be seen that the original vapor substance eilluent from the still 10 is divided into two portions by means of the contact path apparatus 14 and the reflux condenser 71. The vapor from this ap aratus is again divided in the contact pat a paratus 76 into two portions, the high boi ing ortion being discharged as a liquid eilluent t rough the cooler to the top' of the column scrubber- 88, and the low boiling portion being discharged as a vapor eilluent from the contact path apparatus 76, and the reluctantly condensible portions thereof being recovered by being absorbed, dissolved or condensed in the high boiling portion of the same original vapor substance.

While some of the vapors herein referred to as such may partake of the nature of gases, it is to be understood that thev expressions vapor and vapors as used in this speciiicationand the claims are intended to describe eluent vapors and gases.

The expressionliigher boiling condensate fraction or the' like, used in some of the claims, is obviouslyT meant toexclude the lowest boiling of the condensate fractions obtained prior to the absorbingaction.V

Having thus described the invention, whatA certain of the higher boiling of said several condensates other than the lowest boiling of said rcondensates in counter-current contact.

2. The method of refining petroleum oils by separating the heavier oils from the lighter and passing the vapors of the latter through a plurallty ofcondensers which condense and discharge condensate fractions of ,the vapors lof different boiling points, and subjecting the uncondensed vapors from the last condenser to the absorbing action of a higher boiling of said condensate fractions. v

3. The method of refining petroleum. oils by` separating the heavier oils from the lighter and passingthe vapors of the latter through a plurality of condensers, Which condense `and discharge condensate fractions of the vapors of dierent boiling points, and subjecting the uncondensed vapors from the last condenser to the absorbing action ofa mixture of the higher boiling of said con? densate fractions.

4. The method of refining petroleum oils by separating the heavier, oils from the lighter and passing the vapors of the latter through a plurality of condensers, which condense and discharge condensate fractions of the vapors of different boiling points, vsubjecting the uncondensed vapors from the last condenser to the absorbing action of one ofI ,the higher boiling of said condensate fractios, and subjecting the uncondensed vapors remainin `to the absorbing action of a still higher bolling condensate fraction.

5. The method of refining petroleum oils by separating the heavier oils from the lighter and passing the vapors of the latter through a plurality of condensers, which condense and discharge condensate fractions of the vapors of different boiling points, and subjecting the uncondensed vapors from the last condenser to the absorbing action of the higher boiling of said condensate fractions in successi-on from condensates of lower boiling point to those of higher boilin point.

6. The met 10d of refining petroleum oils which consists in irst separating the heavier oils fromA the lighter oils.and' in then subjecting the vapors of the latter to the action of a contactpath apparatus to effect a separation from such vapors of the high boiling constituents as a liquid, 'cooling the same, passing the vapor constituents through a series of condensers 'to form a plurality of condensates of different boiling points, and subjecting the uncondensed vapors from the last condenser to the absorbing action of the higher boilinn` of said condensates.

7. The method of liquefying gas-vapor 'mixtures consisting in passing a stream of the mixtures through a series of cooling zones to liquefy in veach a portion of the mixtures, withdrawing from said zones in separate streams the several liquefied portions of said mixtures, and subjecting the uncondensed eflluent-of the last cooling zone to the absorbingaction of the liquid eiuent from a non-adjacent cooling zone to absorb, dissolve or condense a further portionof the initial gas-vapor mixture.

WALTER E. LUMMUS. 

